Structural performance of prestressed precast high speed railway bridges using high performance concrete

Bridges often need to conform to strict alignment rules for high speed railway (HSR) lines. Generally, the bridges are constructed either from prestressed concrete or steel-concrete composite. Prestressed concrete bridges can be constructed by precast methods, which offer benefits in economies of scale, quality and construction times for long repetitive viaducts. However, currently precast construction utilises conventional concrete strengths, leading to thicker, heavier cross sections to resist the load. High performance concrete (HPC), with its increased strength, can be implemented to reduce the precast segment weights, subsequently reducing substructure and transportation capacities. However, lighter sections could lead to decks more prone to vibrations exceeding acceleration limits. Therefore, the implementation of HPC requires further research, addressed in this thesis, using the most sophisticated and realistic numerical models of the bridge, vehicle, track, wheel-rail interaction and rail irregularities, identified in literature. A suitable benchmark bridge is selected and analysed from a database of concrete HSR bridges. This analysis finds that using track irregularities with wheel-rail contact is mandatory for accurate bridge accelerations, leading to up to 3.75 times larger accelerations than equivalent moving load models. Furthermore, sectional deformations have been found to be non-negligible, with beam element bridge models incapable of exhibiting the wide frequency content of the acceleration response seen in shell elements. A subsequent parametric analysis reduces the geometrical cross sectional dimensions of the precast components, implementing HPC to maintain the structural capacities. The applicability of the acceptable parametric analyses are tested on other bridges, determining more general conclusions for HPC inclusion in HSR bridges. Appropriate reductions in geometry (web, bottom flange and top flange thicknesses down to 66, 75 and 75% of the original value respectively), are identified from the response of the bridge and vehicle, by using HPC up to 96 MPa, contributing to up to 22% lighter precast elements. Appropriate design guidance is subsequently made for better design of HSR bridges to incorporate HPC into precast solutions.Open Acces

‘Music is my AK-47’: performing resistance in Belfast's rebel music scene

This article examines how some Irish republicans have used ‘rebel songs’ as a means to resist the hegemonic power of the British state, and how militant republicanism is invoked musically, through sonic and physical references to gunfire. It explores how the use of rebel songs has changed, the inherent tensions within today's scene, and how republicans attempt to co‐opt other conflicts as a means to strengthen their claim as resistance fighters. The article also analyses more nuanced resistances within the rebel music scene, exploring how competing republican factions use the same music to express opposing political positions, and why some musicians ultimately leave the scene on account of the musical and political restrictions placed upon them. In so doing, the article connects with ongoing attempts to rethink, remap, and develop new approaches to resistance within anthropology, while contributing to the developing subfield of ‘ethnomusicology in times of trouble’

Use of Metagenomic Next-Generation Sequencing to Identify Pathogens in Pediatric Osteoarticular Infections.

BackgroundOsteoarticular infections (OAIs) are frequently encountered in children. Treatment may be guided by isolation of a pathogen; however, operative cultures are often negative. Metagenomic next-generation sequencing (mNGS) allows for broad and sensitive pathogen detection that is culture-independent. We sought to evaluate the diagnostic utility of mNGS in comparison to culture and usual care testing to detect pathogens in acute osteomyelitis and/or septic arthritis in children.MethodsThis was a single-site study to evaluate the use of mNGS in comparison to culture to detect pathogens in acute pediatric osteomyelitis and/or septic arthritis. Subjects admitted to a tertiary children's hospital with suspected OAI were eligible for enrollment. We excluded subjects with bone or joint surgery within 30 days of admission or with chronic osteomyelitis. Operative samples were obtained at the surgeon's discretion per standard care (fluid or tissue) and based on imaging and operative findings. We compared mNGS to culture and usual care testing (culture and polymerase chain reaction [PCR]) from the same site.ResultsWe recruited 42 subjects over the enrollment period. mNGS of the operative samples identified a pathogen in 26 subjects compared to 19 subjects in whom culture identified a pathogen. In 4 subjects, mNGS identified a pathogen where combined usual care testing (culture and PCR) was negative. Positive predictive agreement and negative predictive agreement both were 93.0% for mNGS.ConclusionsIn this single-site prospective study of pediatric OAI, we demonstrated the diagnostic utility of mNGS testing in comparison to culture and usual care (culture and PCR) from operative specimens

Use of Metagenomic Next-Generation Sequencing to Identify Pathogens in Pediatric Osteoarticular Infections.

BackgroundOsteoarticular infections (OAIs) are frequently encountered in children. Treatment may be guided by isolation of a pathogen; however, operative cultures are often negative. Metagenomic next-generation sequencing (mNGS) allows for broad and sensitive pathogen detection that is culture-independent. We sought to evaluate the diagnostic utility of mNGS in comparison to culture and usual care testing to detect pathogens in acute osteomyelitis and/or septic arthritis in children.MethodsThis was a single-site study to evaluate the use of mNGS in comparison to culture to detect pathogens in acute pediatric osteomyelitis and/or septic arthritis. Subjects admitted to a tertiary children's hospital with suspected OAI were eligible for enrollment. We excluded subjects with bone or joint surgery within 30 days of admission or with chronic osteomyelitis. Operative samples were obtained at the surgeon's discretion per standard care (fluid or tissue) and based on imaging and operative findings. We compared mNGS to culture and usual care testing (culture and polymerase chain reaction [PCR]) from the same site.ResultsWe recruited 42 subjects over the enrollment period. mNGS of the operative samples identified a pathogen in 26 subjects compared to 19 subjects in whom culture identified a pathogen. In 4 subjects, mNGS identified a pathogen where combined usual care testing (culture and PCR) was negative. Positive predictive agreement and negative predictive agreement both were 93.0% for mNGS.ConclusionsIn this single-site prospective study of pediatric OAI, we demonstrated the diagnostic utility of mNGS testing in comparison to culture and usual care (culture and PCR) from operative specimens